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Tuesday, December 8, 2020

Kubernetes - hands on practice

------------------------
Kubernetes basic concept
------------------------

1. Create a namespace called frontend

ns-> namespace
[root@master kube]# kc create ns fronend

# kc get ns

2. Create a pod name nginx in frontend namespace. usig nginx image
# kc run nginx --image=nginx -n frontend

[root@master kube]# kc create ns frontend
namespace/frontend created
[root@master kube]# kc run nginx --image=nginx -n frontend
pod/nginx created
[root@master kube]# kc get ns | grep frontend
frontend          Active   2m2s
[root@master kube]# kc get pods | grep nginx
nginx-f89759699-hxfnp   0/1     Pending   0          24d
[root@master kube]#

3. Get list of al lpods in kibe-system namespace and write the output to /root/kube-system-pods.txt

[root@master kube]# kc get pods -n kube-system
[root@master kube]# kc get pods -n kube-system > /root/kube/kube-system-pods.txt

4. Get list of all services across all namespaces and write the output to /root/all-services.txt
[root@master kube]# kc get svc -A
[root@master kube]# kc get svc -A > /root/kube/all-services.txt

Note: -A is shirtcut for --all-namespaces

5. Create a pod named hello with iage busybox and command echo "Hello Workd". Make sure the pod do not restart automatically
[root@master kube]# kc run hello --image=busybox --restart=Never -- echo "HelloWorld kc delete pod pod!"
[root@master kube]# kc get pod

6. Generate a pod manifest file at /root/mypodx.yaml. Pod name should be mypodx with image redis. Make sure you only generate the pod manifest file, you do not have to create the pod.

[root@master kube]# kc run mypod --image=redis --dry-run=client -o yaml >/root/kube/mypodx.yaml

-------------------
Configuration Part
-------------------

1. Create a config map called my-config in namespace called datatab. Use value confa=exvalue. Yo umay want to create namespac if it does not exists.

[root@master kube]# kc create ns datatab
[root@master kube]# kc create cm my-config --from-literal=confa=exvalue --namespace=datatab

2. A configmap al-conf has been created. Expose the value of al-user to a pod named al-pod as AL_USER environment variable. Use redis image for the pod.

cat << EOF > al-pod.yaml
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
    run: al-pod
name: al-pod
spec:
containers:
- image: redis
    name: al-pod
    env:
    - name: AL_USER
      valueFrom:
        configMapKeyRef:
          name: al-conf
          key: al-user
    resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Always
status: {}
EOF

[root@master kube]# kc apply -f al-pod.yaml

3. Create a Pod named secure-pod. Use redis image. Run pod as user 1000 and group 2000

create a spec file:

cat << EOF > secure-pod.yaml
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
    run: secure-pod
name: secure-pod
spec:
securityContext:
    runAsUser: 1000
    runAsGroup: 2000
containers:
- image: redis
    name: secure-pod
    resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Always
status: {}
EOF

[root@master kube]# kc apply -f secure-pod.yaml
[root@master kube]# kc get pods | grep secure

4. Create a pod mainfest file at /root/kube/limitd-pod.yaml with name limited-pod and busybox image. Set memory request at 100Mi and limit at 200 Mi. You do not need to create the pod

[root@master kube]# kc run limited-pod --image=busybox --requests='memory=100Mi' --limits='memory=200Mi' --dry-run=client -o yaml > /root/kube/limited-pod.yaml

[root@master kube]# more /root/kube/limited-pod.yaml
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
    run: limited-pod
name: limited-pod
spec:
containers:
- image: busybox
    name: limited-pod
    resources:
      limits:
        memory: 200Mi
      requests:
        memory: 100Mi
dnsPolicy: ClusterFirst
restartPolicy: Always
status: {}
[root@master kube]#

5. Complete the following tasks
a. Create a secret db-secret with value MYSQL_ROOT_PASSWORD=YoYoSecret and MYSQL_PASSWORD=X0X0Password
[root@master kube]# kubectl create secret generic db-secret --from-literal='MYSQL_ROOT_PASSWORD=YoYoSecret' --from-literal='MYSQL_PASSWORD=XoXoPassword'

b. Create a configmap db-config with value MYSQL_USER=k8s and MYSQL_DATABASE=newdb
[root@master kube]# kc create configmap db-config --from-literal='MYSQL_USER=k8s' --from-literal='MYSQL_DATABASE=mewdb'

c. Create a pod named mydb with image mysql:5.7 and expose all values of db-secret and db-config as environment variable to pod.

Create a spec file

cat << EOF > mydb.yaml
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
    run: mydb
name: mydb
spec:
containers:
- image: mysql:5.7
    name: mydb
    envFrom:
    - configMapRef:
        name: db-config
    - secretRef:
        name: db-secret
    resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Always
status: {}
EOF

[root@master kube]# kc apply -f mydb.yaml
pod/mydb created

6. Create a service account named namaste. Use the service account to create a pod yo-namaste with image nginx
[root@master kube]# kc create sa namaste
serviceaccount/namaste created
[root@master kube]# kc run yo-namaste --image=nginx --serviceaccount=namaste
pod/yo-namaste created
[root@master kube]# kc get pods

--------------------------------
Multi-Container PODs
Complete the following tasks

1. Create a pod mp-hello with image alpine, nginx and consul:1.8.
Use command sleep infinity for alpine comtainer.

# kc run mp-hello --image=alpine --command sleep=infinity

# cat << EOF > np-hello.yaml
[root@master kube]# cat <<EOF > mp-hello.yaml
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
    run: mp-hellp
name: mp-hellp
spec:
containers:
- args:
    - sleep
    - infinity
- image: alpine
    name: mp-hellp

- image: nginx
    name: nginx

- image: consul:1.8
    name: consul

    resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Always
status: {}
EOF

[root@master kube]# kc apply -f mp-hello.yaml
error: error validating "mp-hello.yaml": error validating data: ValidationError(Pod.spec.containers[0]): missing required field "name" in io.k8s.api.core.v1.Container; if you choose to ignore these errors, turn validation off with --validate=false

[root@master kube]# kc apply -f mp-hello.yaml
pod/mp-hellp created
[root@master kube]#

$ sleep 5 && upgrade.sh

Monday, December 7, 2020

Ansible - update / copy file using jinja template

Copy name server info to all web servers
1. Disable NetworkManager service
[root@master ~]# systemctl status/stop/disable NetworkManager

2. Update your config file with correct dns entry
[root@master ~]# cat mydns.conf
nameserver {{ dnsip }}

3. Write your yaml file
[root@master ~]# cat mydns.yaml
- hosts: myweb
vars:
    - dnsip: "8.8.8.8"

tasks:
    - template:
        src: mydns.conf
        dest: /etc/resolv.conf

4. Check your ansible config file
[root@master ~]# ansible --version
config file = /etc/ansible/ansible.cfg

5. Find your inventory file
[root@master ~]# cat /etc/ansible/ansible.cfg | more
[defaults]
inventory      = /root/myhosts
host_key_checking=false

6. Check your inventory record. Set up passwordless authentication (ssh-keygen)
[root@master ~] # cat myhosts
[myweb]
worker1 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh
worker2 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh

7. Run your playbook
[root@master ~]# ansible-playbook mydns.yaml

Ansible - File copy - update DNS record on client machines

Copy name server info to all web servers
1. Disable NetworkManager service
[root@master ~]# systemctl status/stop/disable NetworkManager

2. Update your config file with correct dns entry
[root@master ~]# cat mydns.conf
nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 10.0.2.2

3. Write your yaml file
[root@master ~]# cat mydns.yaml
- hosts: myweb
tasks:
    - copy:
        src: dns.conf
        dest: /etc/resolv.conf

4. Check your ansible config file
[root@master ~]# ansible --version
config file = /etc/ansible/ansible.cfg

5. Find your inventory file
[root@master ~]# cat /etc/ansible/ansible.cfg | more
[defaults]
inventory      = /root/myhosts
host_key_checking=false

6. Check your inventory record. Set up passwordless authentication (ssh-keygen)
[root@master ~] # cat myhosts
[myweb]
worker1 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh
worker2 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh

7. Run your playbook
[root@master ~]# ansible-playbook mydns.yaml

Thursday, December 3, 2020

Ansible - task automation, install, start service and configure web service

Day6- ansible

Ansible

- Control Node
- Managed node
    - Web Server (IP)

- hosts: myweb # myweb comes from
tasks:
- package:
      name: "httpd"
- copy:
      dest: "/var/www/html/index.html"
      content: " for lb testing"

- service:
      name: "httpd"
      state: restarted

- hosts: mylb
tasks:
- name: "Install LB software"
    package:
      name: "haproxy"
~

add template

go to haproxy server and copy this file to your ansible controller node.

For me, I used same server for controller node and proxy.

[root@master ~]# cat lb.yaml
- hosts: myweb # myweb comes from
tasks:
- package:
      name: "httpd"
- copy:
      dest: "/var/www/html/index.html"
      content: " for lb testing"

- service:
      name: "httpd"
      state: restarted

- hosts: mylb
tasks:
- name: "Install LB software"
    package:
      name: "haproxy"

- template:
      dest: "/etc/haproxy/haproxy.cfg"
      src: "haproxy.cfg"

- service:
      name: "haproxy"
      state: restarted

[root@master ~]# ansible-playbook lb.yaml

Go to your LB and check if you can access the sites...

if you have new host, just add it to ansible inventory and lb, run the play, it will configure..
one click, web server is ready and added to lb

Note: if you forget to update LB, adding new server does not work at all.

This concept is call scale -> horizontal scaling.. adding node
veritcal scaling - > adding cpu/ram/disk

go to load balancer, and check the config file...

check under baclend and add new host and rerun the lb.yml file.

add new host (horizontal scaling)

Challanges in terms of management
1. Knowing config file of every software is challanging
2. everytime, we have to go to control node and update new host

if there is a new IP address, update the config file and upload automatically..

we want new IP will be added to haproxy.conf automatically
or say we have old IP and we no longer using and need to be removed..

Task:
On controller node, when you have new IP is detected, configure web server, update the template file for haproxy and upload it to haproxy server?

=======================================================

How to configure docker using ansible
Steps

Note: docker-ce does not come on redhat iso.
1. Configure yum repo for docker
Get url from internet

2. Install docker
docker-ce

3. Start service

4. docker images

5. Run comtainers

Masternode: .50
Managed node: .51/.52

[root@master ~]# ping goo.gl
[root@master ~]# yum list docker-cd

go to your controller node.

# ansible-docs yumrepositry

- hosts: 192.168.10.50
tasks:
- name: setting up docker yum confuration
    yum_repository:
      name: df
      description: EPEL yum repo
      file: external_repo
      baseurl: https://download ....
      gpgcheck: no

# install the package
- package:
      name: "docker-ce"
      state: present

We got error

Now, go to the system and try to install manually.

# yum install docker-ce

error: use '--nobest'

# yum install docker-ce --nobest

It installs successfully
but we want to perform this task using ansible.

google ansible package module
and go to docs.ansible

read the doc, we didn't find anything under package

google ansible yum module

ad-hoc commands,

[root@master ~]# ansible all -m command -a date
worker1 | CHANGED | rc=0 >>
Thu Dec 3 11:40:44 EST 2020
worker2 | CHANGED | rc=0 >>
Thu Dec 3 11:40:44 EST 2020
master | CHANGED | rc=0 >>
Thu Dec 3 11:40:44 EST 2020

Reboot all the machines
[root@master ~]# ansible all -m command -a reboot

reboot web servers
[root@master ~]# ansible myweb -m command -a reboot

rather than package module, use ad-hoc command

- hosts: 192.168.10.50
tasks:
- name: setting up docker yum confuration
    yum_repository:
      name: df
      description: EPEL yum repo
      file: external_repo
      baseurl: https://download.docker.con/linux/centos/7/x86_64/stable/
      gpgcheck: no

# install the package
# - package:
#      name: "docker-ce"
#      state: present

- command: "yum install docker-ce --nobest -v"

you will encounter same kind of problem on hadoop as well.
yum comand does not work with --force

need flag --force

For that you have to use command module and os specific command.
# rpm -ivh hadoop --force

Write a playbook that goes to aws-cloud and create an ec2 instance

LAB2 - Running ansible ad-hoc commands

Running ansible ad-hoc commands

1. Get ansible version
# ansible --version
- Get ansible/python version
- Get the config file location
- and get the inventory file location

2. Check the communication with managed nodes
# ansible all -m ping

3. Copying files to worker node
- Lets google for copy module: ansible copy file module
- search for ansible service module and review the doc and review the example as well.

4. Lets install httpd manually first on one of the worker node
# yum install httpd
# systemctl start httpd
# cd /var/www/html
# cat > index.html
Welcome to my web site !!!

5. go to browser and test it. You should have access to the page.
If you encounter proble, disable firewall, selinux for testing purpose.

6. Now, remove httpd
# systemctl stop httpd
# yum remove httpd -y
# rpm -q httpd # verify
# ls -ld /var/www/html # you can't list this dir

7. Now, go to control node and run ad-hoc command
# ansible --version
# ansible all --list-hosts
# cat > index.html
Welcome to ansible pushed page !!!
# ansible all -m package -a "name=httpd state=present"
# ansible all -m copy -a "src=index.html dest=/var/www/html/"
# ansible all -m service -a "name=httpd state=started"
# ansible worker2 -m service -a "name=httpd state=started"
# ansible worker2 -m copy -a "src=copyme.html dest=/var/www/html/"
go to worker2 node and check
# systemctl status httpd
[root@master ~]# cat copyme.html
Copied from ctrl node
[root@worker2 html]# cat copyme.html
Copied from ctrl node

# ansible 192.169.10.51 -m service -a "name=httpd state=started
-------------------------------
Now, lets go ahead and setup web server.

1. Install httpd package
# ansible all -m package -a "name=httpd state=present"
We are using package module here.

2. Copy webpage to web server
# ansible all -m copy -a "src=copyme.html dest=/var/www/html/"

3. Start web server httpd on managed node from control node
# ansbile all -m service -a "name=httpd state=started"

8. Lets automate this manu task by writing a config file
# cat webpage.yaml
- hosts: myweb
tasks:
    - package: "name: "httpd state=present"
    - copy: "src=copyme.html dest=/var/www/html/"
    - service: "name=httpd state=started"

# ansible-playbook webpage.yaml

[root@master ~]# cat webserver.yaml
- hosts: all
tasks:
- file:
      state: directory
      path: "/dvd1"

- mount:
      src: "/dev/cdrom"
      path: "/dvd1"
      state: mounted
      fstype: "iso9660"
# add entry to fstab
# task is a list of three task such as file, mount and yum.
# these belongs to same block of code, so same space..

- yum_repository:
      baseurl: "/dvd1/AppStream"
      name: "mydvd1"
      description: "My yum repo"
      gpgcheck: no

- yum_repository:
      baseurl: "/dvd1/BaseOS"
      name: "mydvd2"
      description: "My yum repo 2"
      gpgcheck: no

- package:
      name: "httpd"
      state: present
- copy:
      dest: "/var/www/html/index.html"
      content: "Welcome to my web page. Enjoy !!!"

- firewalld:
      port: "80/tcp"
      state: enabled
      permanent: yes
      immediate: yes
[root@master ~]#
[root@master ~]# cat myhosts
#[masterserver]
#master ansible_user=sam

#[WebServer]
#worker1
#worker1 ansible_user=sam
#worker2 ansible_user=sam
[mylb]
master ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh
[myweb]
worker1 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh
worker2 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh
[root@master ~]#

[root@master ~]# cat lb.yaml
- hosts: myweb # myweb comes from
tasks:
- package:
      name: "httpd"
- copy:
      dest: "/var/www/html/index.html"
      content: " for lb testing"

- service:
      name: "httpd"
      state: restarted

- hosts: mylb
tasks:
- name: "Install LB software"
    package:
      name: "haproxy"

- template:
      dest: "/etc/haproxy/haproxy.cfg"
      src: "haproxy.cfg"

- service:
      name: "haproxy"
      state: restarted
[root@master ~]#

[root@master ~]# cat repo.docker.repo
- hosts: 192.168.10.50
tasks:
- name: setting up docker yum confuration
    yum_repository:
      name: df
      description: EPEL yum repo
      file: external_repo
      baseurl: https://download.docker.con/linux/centos/7/x86_64/stable/
      gpgcheck: no

# install the package
- package:
      name: "docker-ce"
      state: present

- command: "yum install docker-ce --nobest -v"

[root@master ~]#

[root@master ~]# cat copyme.txt
Copied from ctrl node
[root@master ~]#

[root@master ~]# cat web.html
Welcome to my page for ansible
[root@master ~]#

[root@master ~]# cat pod-definition.yml
apiVersion: v1

kind: Pod

metadata:
name: myapp-pod
labels:
    app: myapp

spec:
containers:
     - name: nginx-container
       image: nginx
[root@master ~]#

Wednesday, December 2, 2020

Lab1 - Install and configure ansible, and install package on worker node using ansible

1. Check if ansible is installed on your system.
# rpm -q ansible
# rpm -qa grep ansible

2. Check/setup your repo
# yum repolist
# yum install ansible

No match for argument: ansible

3. Install ansible using pip
# python -V
# pip3 install ansible
# ansible -version # Note the config file location

4. List your ansible hosts
# ansible all --list-hosts

5. Define your inventory of hosts
# vi /root/myhosts
w1 192.168.10.51
w2 192.168.10.51

google for ansible inventory, read through it...

# vi /etc/ansible/ansible.cfg
# add the following contents
[defaults]
inventory = /root/myhosts
wq!

# ansible all --list-hosts
# ansible all -m ping

6. Now, lets go ahead and install one software package on worker node.
- Login to worker node and check if firefox is installed, If yes, remove it.
# rpm -q firefox
# rp remove firefox

7. Google for ansible package module
go to docs.ansible and read through, look at the example.
check state -> present/absent

# ansible all -m package -a "name=firefox state=present"
error: install sshpass program

# rpm -q sshpass
# yum install sshpass
# pip3 install sshpass
still failed to install.

Google for epel release package, download and install
# wget <http://path-to-epel>

# rpm -ivh epel-release-latest-8.noarch.rpm

# yum repolist

# yum install sshpass

# ansible all -m package -a "name=firefox state=present"
[root@master ~]# ansible all -m package -a "name=firefox state=present"

[root@worker1 html]# rpm -q firefox
package firefox is not installed
[root@worker1 html]# rpm -q firefox
firefox-68.7.0-2.el8_1.x86_64

[root@worker2 html]# rpm -q firefox
package firefox is not installed
[root@worker2 html]# rpm -q firefox
firefox-68.7.0-2.el8_1.x86_64

[root@master ~]# ansible --version
ansible 2.9.14
config file = /etc/ansible/ansible.cfg

[root@master ~]# more /etc/ansible/ansible.cfg
[defaults]
inventory      = /root/myhosts

[root@master ~]# cat myhosts
#[masterserver]
#master ansible_user=sam

#[WebServer]
#worker1
[mylb]
master ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh

[myweb]
worker1 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh
worker2 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh

[root@master ~]# cat /etc/hosts
192.168.56.5    master master.expanor.local
192.168.56.6    worker1 worker1.expanor.local
192.168.56.7    worker2 worker2.expanor.local

Ansible-Install and configure HA-Proxy using ansible

Ansible Notesday 5
-------------------------

LB and reverse proxy
--------------------

how to configure load balancer and reverse proxy

webserver
Apache (http) -> webserver:80 -> web page -html

-> we have apache web server running on port 80.

use case,
so, user within the organization or from remote site access the site.

one server has limited resources such as cpu/mem and it can handle certain number of load/connection.

so, if user keep growing, you have to upgrade server power. what if you have millions of users/visitors to your site?

this is a big challange. we have on single server and it is working on its full capcacity.

what can we do to increase the limit?
we already increase the max limit. how can we solve it?

we can launch a new server instances (VM, container) with new IP and configure the web server the same way as the first one.

Challanges?
You have two servers with two IP. so, you have to let your user to connect to new IP. so, you have two different IP to access it. again, your user growth increase and you have new IPs. this sounds not logical.

say, you have 1000s of computer, you can't give all IP to your users. it will be hectic for user so, to get ride of this problem, we will have one server with say ip of .100.

so user will connect to .100. now, any request comes to .100, it will forward request to web server.

And web server thinks .100 is client and returns the request to .100. And .100 forward user request.
IP .100 is never a web server or a client. This is a proxy, so it behaves proxy and reverse proxy.

server serving on other's behave,

firewall
in the web server, you don't have to allow all IP address, you can only allow .100 since request always comes through .100.
so you can enable .100 on firewall.
we have extra level of security here.

.100 [ Proxy server]
-- Webserver1
-- webserver2
-- webserver3

- all the request comes to .100, pass traffic to webserver1
- when load increase add new web server to reverse proxy.
- as soon as first request comes, it goes to w1 and second goes to s2.
- So, it is balancing the load between the servers.
- if load increases, we can add new web server and register with prxy and it is available for service.

For this kind of setup, we can use ansible to configure.

in real scenario, the .100 server we give them name such as host or domain.
so, these names might not be the real physical server. these may be just load balancer and they don't go down.

====================

# yum install php
systemctl status httpd
# cd /var/www/html

<pre>
<?php>
print `ifconfig`;
</php>
</pre>

========================

Configure LB and proxy

Step1. Install haproxy - comes on DVD
# yum install haproxy

Step2. Configure haproxy

# /etc/haproxy/haproxy.cfg

frontend main
    bind *:5000

change it to port 8080

frontend main
    #bind *:5000
    bind *:8080

go down you will see backend

    default_backend             app

backend app
    balance     roundrobin
    server webserver1 192.168.56.6:80 check
    server webserver2 192.168.56.7:80 check

here you will define list of all backend servers.

[root@master ~]# systemctl start haproxy

systemctl start/enable haproxy

Now, go to web server and create test page.

get your IP address and try to access
http://192.168.56.5:8080/

keep refreshing the page, you will see different content.

We manually configured the page.

- hosts: 192.168.56.6,192.168.56.6    # all to install software on all or define individually
tasks:

There is one option available in inventory to group them. and give them group name say web or load balancer.

[mylb]
master ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh
[myweb]
worker1 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh
worker2 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh

# cat lb.yaml

- hosts: myweb    # myweb comes from
tasks:
- package:
      name: "httpd"

- hosts: mylb
tasks:
- package:
      name: "haproxy"

# ap lb.yaml
# ansible-playbook lb.yaml

# cat lb.yaml

- hosts: myweb    # myweb comes from
tasks:
- package:
      name: "httpd"

- hosts: mylb
tasks:
- package:
      name: "haproxy"

-step2: config

step3. service haproxy

lets say you configure load balancer: .5
webserver: .6/.7

say, we have load come up, and need to configure new web server.

only thing you have to do is, on inventory, add new IP address under web, it will be configured a web server.

the chanllange is to go to load balancer, and add entry to backend app with new IP.

with the help of ansible, when new ip added to inventory, the config of haproxy will be updated.

Accessing HAProxy stats page
---------------------------

Configuration of haproxy config file

[root@master ~]# cat /etc/haproxy/haproxy.cfg
#---------------------------------------------------------------------
# Example configuration for a possible web application. See the
# full configuration options online.
#
#   https://www.haproxy.org/download/1.8/doc/configuration.txt
#
#---------------------------------------------------------------------

#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global
    # to have these messages end up in /var/log/haproxy.log you will
    # need to:
    #
    # 1) configure syslog to accept network log events. This is done
    #    by adding the '-r' option to the SYSLOGD_OPTIONS in
    #    /etc/sysconfig/syslog
    #
    # 2) configure local2 events to go to the /var/log/haproxy.log
    #   file. A line like the following can be added to
    #   /etc/sysconfig/syslog
    #
    #    local2.*                       /var/log/haproxy.log
    #
    log         127.0.0.1 local2

    chroot      /var/lib/haproxy
    pidfile     /var/run/haproxy.pid
    maxconn     4000
    user        haproxy
    group       haproxy
    daemon

    # turn on stats unix socket
    stats socket /var/lib/haproxy/stats

    # utilize system-wide crypto-policies
    ssl-default-bind-ciphers PROFILE=SYSTEM
    ssl-default-server-ciphers PROFILE=SYSTEM

#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
    mode                    http
    log                     global
    option                  httplog
    option                  dontlognull
    option http-server-close
    option forwardfor       except 127.0.0.0/8
    option                  redispatch
    retries                 3
    timeout http-request    10s
    timeout queue           1m
    timeout connect         10s
    timeout client          1m
    timeout server          1m
    timeout http-keep-alive 10s
    timeout check           10s
    maxconn                 3000

#---------------------------------------------------------------------
# main frontend which proxys to the backends
#---------------------------------------------------------------------
frontend main
    bind *:8080
    #bind *:5000
    acl url_static       path_beg       -i /static /images /javascript /stylesheets
    acl url_static       path_end       -i .jpg .gif .png .css .js

    use_backend static          if url_static
    default_backend             app

#---------------------------------------------------------------------
# static backend for serving up images, stylesheets and such
#---------------------------------------------------------------------
backend static
    balance     roundrobin
    server      static 127.0.0.1:4331 check

#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend app
    balance     roundrobin
    server webserver1 192.168.56.6:80 check
    server webserver2 192.168.56.7:80 check

frontend stats
    bind *:8084
    stats enable
    stats uri /stats
    stats refresh 10s
    stats admin if LOCALHOST
[root@master ~]#

Now access the STATS page by going to masternode (proxy server) IP:8084/stats

http://master:8084/stats

you will see web interface.

-----------------------------------------------

[root@master ~]# ansible --version
ansible 2.9.14
config file = /etc/ansible/ansible.cfg

[root@master ~]# more /etc/ansible/ansible.cfg
[defaults]
inventory = /root/myhosts

[root@master ~]# cat myhosts
#[masterserver]
#master ansible_user=sam

#[WebServer]
#worker1
[mylb]
master ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh

[myweb]
worker1 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh
worker2 ansible_user=root ansible_ssh_pass=changeme ansible_connection=ssh

[root@master ~]# cat /etc/hosts
192.168.56.5    master master.expanor.local
192.168.56.6    worker1 worker1.expanor.local
192.168.56.7    worker2 worker2.expanor.local

[root@master ~]# cat lb.yaml
- hosts: myweb # myweb comes from
tasks:
- package:
name: "httpd"

- hosts: mylb
tasks:
- package:
name: "haproxy"